Differential Gene Expression in Plants Stressed by the Peroxidizing Herbicide Oxyfluorfen
§Barbara Lederer, Oliver Carsten Knörzer and Peter Böger*
Lehrstuhl für Physiologie und Biochemie der Pflanzen, Universität Konstanz, D-78457 Konstanz, Germany. Fax: +49Ð7531Ð88 3042.
E-mail: Peter.Boeger@uni-konstanz.de
* Author for correspondence and reprint requests
Z. Naturforsch.54c,764Ð770 (1999); received November 8, 1998/March 6, 1999 Antioxidative Enzymes, Lipid Peroxidation, Oxidative Stress, Oxyfluorfen, Protoporphyrin IX
The response of plants to the peroxidizing herbicide oxyfluorfen was investigated. The action of thisp-nitrodiphenyl ether is based on inhibition of plastidic protoporphyrinogen oxidase, which leads to accumulation of protoporphyrin IX in the cytosol yielding reactive oxygen species by light activation. The induction of activities of antioxidative enzymes was followed inNicotiana tabacum plants, var. BelW3. Glutathione reductase activity was ele- vated by 75% compared to control, monodehydroascorbate reductase by 65% and glutathi- oneS-transferase by 110%. The mRNA of ascorbate peroxidase and catalase isoform 2 was induced, the catalase isoform 1 was reduced. These findings were confirmed and supported by measuring enzymatic activity changes in photoheterotrophically grown soybean (Glycine max) suspension cultures. To find a possible involvement of compounds regulating oxidative stress response, we investigated the influence of salicylic acid and BTH (benzo(1,2,3)thiadia- zole-7-carbothioic acidS-methylester), both inducers of pathogen defense, on soybean cell suspension cultures. The specific activities of glutathione reductase, monodehydroascorbate reductase and glutathioneS-transferase increased strongly, comparable to oxyfluorfen treat- ment. Both compounds protected the cells against oxyfluorfen-induced lipid peroxidation and alleviated the accumulation of protoporphyrin IX.
